Comparison of cancer chemotherapeutic agents in asynchronous and synchronous 9L cells

The 9L rat brain tumor model for pre-clinical investigation of radiation-chemotherapy interactions

The rat 9L gliosarcoma brain tumor model has been used for more than thirty years to investigate a variety of potential therapeutic agents, combinations, schedules, and approaches that might be applicable to the management of high-grade malignant brain tumors in man. When tumor cells are implanted intracerebrally, a solid tumor grows until its mass results in the death of the animal, typically between 20 and 30 days postinoculation. Radiation therapy (either single or fractionated doses) is effective at prolonging survival in a dose-dependent manner. Numerous cancer chemotherapeutic agents, by a variety of doses, schedules, and routes of delivery, have demonstrated therapeutic efficacy in the 9L model. The combination of radiation and agents such as AZQ, BCNU, bleomycin, and cis-platinum has resulted in prolongation of survival that is significantly better than either agent used alone, without exceeding the tolerance of critical normal tissues. These pre-clinical data suggest that combining standard fractionated radiation therapy with appropriate concomitant cytotoxic chemotherapeutic agents might benefit patients with high-grade brain tumors.

Reduced variation in the clonogenic assay obtained by standardization of the cell culture conditions prior to drug testing on human small cell lung cancer cell lines

An advantage of established tumor cell lines compared to fresh human tumor specimens used in sensitivity assessments is the possibility of repeated experiments. Ultimately a database of sensitivity profiles on a panel of cell lines can be made and the sensitivity to new drugs compared with historical data. A prerequisite of this strategy is a minimal interexperimental variation. The sensitivity of eight human small cell lung cancer cell lines to adriamycin, daunomycin, aclacinomycin A, and mitoxantrone was tested in the clonogenic assay. A covariation in the sensitivity to the drugs emphasized the importance of simultaneous drug testing on the same batch of cells. On one cell line (NCI-N592) the interexperimental variation was further evaluated and a significant correlation was found between preexposure culture conditions, size of S-phase, and sensitivity to adriamycin, daunomycin, and mitoxantrone. Rigorous standardization of the growth conditions prior to clonogenic assay reduced the variation in the sensitivity to adriamycin from a factor of five to only 10-15%. It is concluded that simultaneous experiments on the same batch of cells in drug comparisons should be used if possible. Specification and standardization of culture conditions are necessary in the comparison of drugs tested in different experiments. Inclusion of the same reference drug in all experiments may further increase the validity of comparisons in different experiments.